This invention relates to an improved electric discharge machine.
An electric discharge machine has numerous applications, such as machining of materials with poor machinability, and can be used to generate almost any complicated geometry. Electric-discharge machining is based on the principle of erosion of metals by spark discharges. The discharge occurs when a potential difference between a tool and a workpiece is large enough to cause a breakdown in a dielectric fluid or work fluid such as an oil. The discharge is rapidly repeated, and each time a small amount of workpiece material is removed so as to produce particles.
The cleanliness of the work fluid has a significant effect on occuracy of the machining. If many particles removed from workpieces are suspended between a tool and a workpiece in the work fluid, the discharge easily occurs, so that rates of metal removal can not be precisely controlled.
To ensure that the work fluid is clean, the work fluid containing the removed particles has been filtered with a filter paper or a filter cloth coated with clay or diatomaceous earth.
However, in the case of an electric discharge machine equipped with such a conventional filter, the replacement of clogged up filters is often required. Thus, the workability is decreased. Also, nonuniformity of a coating formed on a filter cloth allows some removed particles to pass through the filter.